This invention relates to apparatuses and methods for sensing impurities in water.
It is known to determine the amount of organic carbon in water being tested by oxidizing the organic carbon in a sample of water and measuring the amount of carbon dioxide obtained by such oxidation. One class of techniques and apparatus for measuring organic carbon are continuous in operation. In a continuous process, the organic carbon in water is oxidized as the water flows through an ultraviolet reactor and the amount of water flowing through the reactor is measured. The carbon dioxide formed by oxidizing the organic carbon in the measured water is also measured to provide an indication of the amount of organic carbon in a unit of water.
In a prior art continuous process for measuring the total organic content of water, each of the stages for oxidation of carbon has its own ultraviolet source and may have its own source of oxidizing agent and/or oxygen or there is a single ultraviolet source in a single stage.
The prior art apparatuses and techniques for measuring the total organic carbon content of water has several disadvantages, such as for example: (1) there is a tendency for some of the carbon dioxide to escape before it is collected and measured; (2) in those embodiments in which several ultraviolet light sources are used, the cost is high; and (3) it is difficult to obtain complete oxidation of the organic carbon.
Certain prior art patents disclose the flow of water in a helical path adjacent to an ultraviolet lamp for the purpose of sterilization or purification of water. However, these patents do not need residence chambers that interrupt the helical flow or bubble-size reduction provisions nor are they carbon measuring apparatus. They are not analytical instruments at all and are not concerned with the completeness of oxidation of carbon as an approach to measuring carbon content.
Some such patents and patent applications are U.S. Pat. Nos. 4,008,045; 5,675,153; 5,069,885; 2,501,290; Canadian Patent 674,555; European patent application 0202891; German Offenlegungsschrift 2,327,084; and French Patent 1,278,161.